If you don't want to spend effort in supporting your site for IE6 you could possibly use any one approach in the below URL.
These approaches suggests the user to download any of the advanced browsers like IE7+, Firefox 3+, Safari 3+, Opera 9.5+ or Google Chrome
http://garmahis.com/tools/ie6-update-warning/
But, that's about IE6. I believe you should still support IE7.
